Thesis (Ph.D.)--McMaster University, 2005. / Advisor: R.G. Drysdale. Includes bibliographical references (p. 270-276). Also available online.

Thesis (Ph. D.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2006. / Includes bibliographical references (p. 263-270).

Thesis (MScEng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Smectite clay minerals are among the most common minerals in subduction zone megathrusts faults at shallow depth and in landslide decollements. Consequently, deformation processes at seismic slip rates (ca. 1 m/s) in smectites contribute to control the mechanics of megathrust earthquakes and landslide collapses. To investigate the deformation processes, rotary shear experiments on smectite-rich gouge layers (70/30 wt.% Ca-montmorillonite/opal) were performed. The experiments were conducted at ambient temperature and at 5 MPa normal stress. The gouges were sheared under vacuum (<0.001 mbar) and room humidity (i.e., water depleted) or in the presence of liquid water (i.e., water rich) conditions, at slip rates of 0.0003 <V <1.5 m/s and displacements of 0.1 <d <30 m. The temperature evolution with slip was measured with thermocouples and modelled numerically. Permeability of the gouge layer was measured with the pore pressure oscillation method prior to the rotary experiments. Before and after the experiments, the mineral and amorphous material content in wt.% were determined via quantitative X-ray powder diffraction and the microstructures investigated via scanning and transmission electron microscopy. The activation of deformation processes was strongly controlled by the water content of the gouge layers. Under water depleted conditions, grainsize reduction producing nanoparticles controlled the evolution of the friction coefficient f at all slip rates. Coseismic dynamic weakening (f = 0.2 - 0.3) occurred by combined thermal decomposition or melting (with decreasing water content) and pressurization of water released by dehydration of smectite interlayer. Under water rich conditions, grain size reduction was minor and development of nano-foliations occurred. At all slip rates, the friction coefficient rapidly decreased at the onset of slip. The large initial weakening (to f <0.15) was due to the presence of a film of water lubricating the surfaces of the sub-parallel smectite grains forming the nano-foliation in combination with shear-enhanced water pressurization. Then, friction coefficient evolved depending on the balance between dissipation of pore pressures, dehydration of smectite interlayer and thickening of the nano-foliation layers. At higher displacement and slip rates, sustained dynamic weakening was aided by vaporization of pore water. Expulsion of water determined a switch to deformation processes typical of water depleted conditions. In nature, the presence of liquid water in smectites has a lubricating effect, pressurizes the slipping zone and renders the smectite-rich gouges prone to accommodate large seismic slips. During megathrust earthquakes, such lubricating effect may result in the easy propagation of seismic ruptures in smectite- and water-rich sediments at shallow depths. Similarly, the presence of water can promote large displacements during landslide collapse.

The study presented aims to provide the most viable seismic retrofit solution for rural masonry. Muzffarabad is one such region where excess of unreinforced masonry structures claimed thousands of lives during 2005 earthquake. Field study was conducted in the region to familiarize with the dynamics of local construction industry before suggesting a suitable retrofit solution. Polypropylene (PP-) band retrofit has been selected as the most viable solution for retrofitting existing masonry structures in terms of cost, material availability and ease of application. To prove the efficiency of PP-band retrofit, numerical simulations and laboratory tests were conducted to assess the seismic efficiency of PP-band retrofit. Material tests were conducted in accordance with BS-EN to familiarize with the mechanical properties of locally available materials in Kashmir region and to provide material data for numerical analysis. Tests revealed lower strength and elasticity for bricks in comparison to materials found in developed countries, due to the unregulated and non-standardized manufacturing of masonry units and high water content in mortars. Shake table tests were conducted to test the effectiveness of PP-band retrofit masonry under dynamic vibrations. Results show that PP-band retrofit can enhance the post peak performance by at least 7 times in comparison to non-retrofit specimen. Real-scale structure retrofit with PP-band survived accelerations of up to 2g without any life-threatening damage, thus, proving to be an economic and efficient strengthening solution for rural communities. Following the shortcomings observed in Room-1, connection detail for PP-bands in Room-2 was revised to achieve a 100% performance enhancement. Numerical models were developed to predict cracks in masonry and analyse diagonal compression test models, in accordance with ASTM standards. The results showed 30% higher residual strength after cracking for PP- band retrofit masonry and the wall integrity was maintained for higher deformations.

No description available.

Performance-based earthquake engineering is an emerging field of study that complements the prescriptive methods that the design codes provide to ensure adequate seismic performance of structures. Accounting for uncertainties in the performance assessments forms an important component in this area. In this context, the present study focuses on two broad themes; first, treatment of uncertainties and the application of the first-order reliability method (FORM) in finite-element reliability analysis, and second, the seismic risk assessment of reinforced concrete structures for performance states such as, collapse and monetary loss. In the first area, the uncertainties arising from inherent randomness (“aleatory uncertainty”) and due to the lack of knowledge (“epistemic uncertainty”) are identified. A framework for the separation of these uncertainties is proposed. Following this, the applicability of FORM to the linear and nonlinear finite-element structural models under static and dynamic loading is investigated. The case studies indicate that FORM is applicable for linear and nonlinear static problems. Strategies are proposed to circumvent and remedy potential challenges to FORM. In the case of dynamic problems, the application of FORM is studied with an emphasis on cumulative response measures. The limit-state surface is shown to have a closed and nonlinear geometric shape. Solution methods are proposed to obtain probability bounds based on the FORM results. In the application-oriented second area of research, at first, the probability of collapse of a reinforced concrete frame is assessed with nonlinear static analysis. By modelling the post-failure behaviour of individual structural members, the global response of the structure is estimated beyond the component failures. The final application is the probabilistic assessment of monetary loss for a high-rise shear wall building due to the seismic hazard in the Cascadia subduction zone. A 3-dimensional finite-element model of the structure with nonlinear material models is subjected to stochastic ground motions in the reliability analysis. The parameters for the stochastic ground motion model are developed for Vancouver, Canada. Monetary losses due to the damage of structural and non-structural components are included. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

No description available.

A semi-analytical method of dynamic analysis, capable of predicting both the magnitude and pattern of earthquake induced deformations, is presented. The analysis is based on a modulus reduction approach which uses a reduced modulus to simulate the softening induced in soils during cyclic loading. The effects of the inertia forces developed during dynamic loading on the induced deformations are also included through an appropriate selection of the reduced modulus. The reduced modulus is utilized in a static stress-strain analysis to predict the magnitude and pattern of the deformations induced during earthquake loading. The appropriate modulus reduction is determined from laboratory tests on undisturbed soil samples. Three methods of computing a suitable post-cyclic modulus were investigated but only the cyclic strain approach, in which the modulus is determined from cyclic loading tests that duplicate the field stress conditions, yields reductions of sufficient magnitude to provide realistic estimates of earthquake induced deformations. The modulus reduction analysis was used to predict the deformations occurring during dynamic loading of a model tailings slope in a laboratory shaking table test and of the Upper San Fernando Dam during the earthquake of February, 1971. These studies showed that the modulus reduction analysis is capable of reproducing the dynamically induced deformations and that reductions in the modulus of up to 1000 times may be required. Unfortunately, limitations of the testing equipment and inadequacies in the available data required that the appropriate modulus reductions could not be determined entirely through laboratory and field investigations. Some assumptions were necessary in selecting the reduced modulus values used in the analyses. Although these case studies were, hence, unable to provide full verification of the proposed method, they do demonstrate the reliability and simplicity of the analysis as a method of assessing the performance of soil structures during earthquake loading. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Background:  Earthquakes and other natural disasters have increased over recent years, more people around the world are living with disabilities. The physical therapists have an important role to increase function and restore quality of life. Although it is stated that early rehabilitation intervention is an essential part of the health response there is limited information about the work and the experiences from physical therapists.  Aim: The aim of this study is to examine physical therapists’ experiences after the earthquakes in Nepal 2015.  Design: This study had a qualitative exploratory design, based on five individual semi-structured interviews using the communication platform zoom. The data was analysed by a qualitative content analysis and had an inductive approach.   Result: The physical therapists’ describes a chaotic situation, the psychological vulnerability in patients made it challenging to motivate and keep the patients focused on their rehabilitation. The huge influx of patients made it hard for the physical therapists to manage their time and led to compromised treatments and the need of early discharge of patients. The physical therapists had dual experiences about their role in the healthcare teams. There was a clear system on how to prioritize the patients based on severity of injuries. Conclusion: This study showed that physical therapists in Nepal had an important role from acute care to follow-up after the earthquakes. The study provides an insight from physical therapists in disaster settings and may contribute to identify barriers in performing their work tasks in future disaster settings. / Bakgrund: Jordbävningar och andra naturkatastrofer har ökat de senaste åren, fler människor runt om i världen lever med kvarstående funktionshinder. Fysioterapeuterna har en viktig roll genom att öka funktionen och återställa livskvaliteten hos dessa patienter. Även om det tydligt anges att en tidig rehabiliteringsinsats är en väsentlig del av arbetet finns det begränsad information om erfarenheterna från fysioterapeuter. Syfte: Syftet med denna studie är att undersöka fysioterapeuters erfarenheter efter jordbävningarna i Nepal 2015. Metod: Denna studie hade en kvalitativ utforskande design, baserad på fem individuella semistrukturerade intervjuer med hjälp av kommunikationsplattformen zoom. Data analyserades med kvalitativ innehållsanalys och hade en induktiv ansats. Resultatsammanfattning: Fysioterapeuterna beskriver en kaotisk situation, den psykologiska sårbarheten hos patienter gjorde det svårt att motivera och hålla patienterna fokuserade på deras rehabilitering. En stor tillströmning av patienter gjorde det svårt för fysioterapeuterna att hantera sin tid och detta ledde till att behandlingar behövde kompromissas och ökade behovet av tidig utskrivning av patienter. Fysioterapeuterna hade tvetydiga erfarenheter av sin roll i vårdteamet. Det fanns ett tydligt system för hur man skulle prioritera patienterna baserat på svårighetsgraden av skador. Slutsats: Denna studie visar att fysioterapeuter i Nepal hade en viktig roll för patienten efter jordbävningarna, en roll som sträcker sig från akutvården till uppföljning. Studien ger tydlig insikt i hur fysioterapeuterna upplevde sitt jobb vilket skulle kunna bidra till identifiering av hinder för fysioterapeuter i utförandet sina uppgifter vid framtida katastrofsituationer.